• Korean Chemical Engineering Research
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• 제60권3호
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• pp.459-467
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• 2022

Pt, PtSn 촉매를 제조한 후, 재분산 연구를 위해 수소분위기에서 소결시킨 후 여러 온도에서 산소처리를 적용하여 백금주석입자의 재분산 정도를 확인하고, 프로판 탈수소 반응실험으로 촉매의 활성을 측정하여 촉매의 물리적, 화학적 상태 변화와 활성의 관계를 이해하고자 하였다. 재분산 처리에 따른 촉매 활성 금속의 상태 및 촉매 입자 간 상호작용 등을 보기 위해 X-선 회절분석(XRD), CO-화학흡착(CO-pulse chemisorption), 수소 승온환원(H₂-TPR) 분석을 실시하였다. 산소 재분산 처리 조건에 따라 백금의 분산도 및 입자 크기, 촉매의 결정상 및 환원 거동이 달라지는 것을 확인하였다. 촉매를 재분산 처리하였을 시 500 ℃에서 산소 처리한 촉매가 가장 높은 전환율과 활성회복률을 보였다. 500 ℃로 산소 처리한 촉매가 백금의 분산도도 비교적 높게 나타나고, 평균 입자 크기가 작아지는 것을 XRD와 CO-화학흡착 결과로부터 확인하여 백금주석입자가 재분산되는 것을 알 수 있었다. 이러한 산소처리에 의한 재분산으로 인해 촉매활성이 회복된다는 것을 알 수 있었고, 백금보다 백금주석 촉매의 활성회복률이 더 높았다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.373-373
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• 2012

We fabricated conductive zinc oxide (ZnO) thin film at low temperature by UV-enhanced atomic layer deposition. The atomic layer deposition relies on alternate pulsing of the precursor gases onto the substrate surface and subsequent chemisorption of the precursors. In this experiment, diethylzinc (DEZ) and $H_2O$ were used as precursors with UV light. The UV light was very effective to improve the conductivity of the ZnO thin film. The thickness, transparency and resistivity were investigated by ellisometry, UV-visible spectroscopy and Four-point probe.

• Macromolecular Research
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• 제9권1호
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• pp.45-50
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• 2001

Formation of bound rubber depends on the filler-polymer interactions including physical adsorption, chemisorption, and mechanical interaction. Bound rubbers consist of tightly and loosely bound ones. Styrene-butadiene rubber (SBR) is composed of styrene, 1,2-, cis-1,4-, and trans-1,4-units. Filler-polymer interactions of each components of SBR with fillers, carbon black and silica, were studied by analysis of microstructure of the bound rubber. Filler-polymer interaction of the 1,2-unit with the fillers was found to be stronger than those of the other components and this phenomenon was shown more clearly in the tightly bound rubber.

• 진공이야기
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• 제1권1호
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• pp.11-16
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• 2014

A variety of metal vacuum systems displays the celebrated 1/t pressure, namely, power-law dependence on time t, with the exponent close to unity, as to the origin of which there has been long-standing controversy. Here we propose a chemisorption model for water adsorbates, based on the argument for 2D fermion behavior of water adsorbed on a metal surface, and obtain analytically the power-law behavior of pressure with an exponent unity. Further, the model predicts that the pressure should depend on the temperature T according to $T^{1.5}$, which is indeed confirmed by our experiment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2006년도 제30회 학술논문발표회 초록집
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• pp.81-81
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• 2006

• Korean Chemical Engineering Research
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• 제52권5호
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• pp.678-687
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• 2014

The catalytic performance of silicon carbide supported nickel catalysts modified with or without second metal (Co, Cu and Zn) for the methanation of CO has been investigated in a fixed-bed reactor using a feed consisting of 25% CO and 75% $H_2$ without any diluent gas. It has been found that the introduction of Co species can clearly improve the catalytic activity of Ni/SiC catalyst, whereas the addition of Cu or Zn can result in a significant decrease in the catalytic activity. The characterizations by means of XRD, TEM, XPS, CO-TPD and $H_2$-TPR indicate that the addition of Co could decrease the particle size of active metal, increase active sites on the surface of methanation catalyst, improve the chemisorption of CO and enhance the reducibility of methanation catalysts. Additionally, the special interaction between Co species and Ni species is likely favorable for the dissociation of adsorbed CO on the surface of catalyst, and this may also contribute to the high activity of 5Co-Ni/SiC catalyst for CO methanation reaction. For 5Cu-Ni/SiC catalyst and 5Zn-Ni/SiC catalyst, Cu and Zn species could cover partial nickel particles and decrease the chemisorption amount of CO. These could be responsible for the low methanation activity. In addition, a 150h stability test under 2 MPa and $300^{\circ}C$ showed that 5Co-Ni/SiC catalyst was very stable for CO methanation reaction.

• 한국환경보건학회지
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• 제23권2호
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• pp.57-63
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• 1997

This study was carried out to find the adverse health effects of ozone by papers, the potential indoor sources of ozone by papers, and then the removal mechanism of ozone by experiments. The exposure of individuals to excessive levels of ozone both in the industrial and ambient environment is a continuing public health concern. Ozone indoors may play a role in generating secondary pollutants that may have adverse health effects. The removal efficiency of ozone was studied by (1) the effect of concentration on breakthrough time, (2) the effect of flow rate on breakthrough time, (3) the effect of adsorbent's weight on breakthrough time, (4) the effect of temperature on breakthrough time, (5) the application of Langmuir's isotherm equation in using activated carbon. The followings are the conclusions that were derived from this study. 1. In the effect of concentration on breakthrough time, the adsorption capacity of activated carbon was inversely proportional to ozone concentratuion (0.1, 0.2, 0.3 ppm). 2. In the effect of flow rate on breakthrough time, the service life of activated carbon was inversely proportional to flow rate (2, 8, 14l/min). 3. The difference in removal efficiency of ozone between weights(100 mg and 150 mg) was seen. And when weight of activated carbon was 100 mg and 150 mg, pressure loss was 4-5mmHg and 6-7mmHg, respectively. It is required to study relations among flow rate and adsorbent's weight and ventilation quantity, too. 4. Generally, Langmuir's equation, one of the oldest and most used frequently isotherm equation, applies to chemisorption. In case of ozone, when the weight of activated carbon was 70 mg and temperature 40, slope(1/a) was $6.25\times 10^{-1}$ and intercept(1/ab) was $1.9\times 10^{-4}$ (average r=0.94).

• Bulletin of the Korean Chemical Society
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• 제23권2호
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• pp.205-214
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• 2002

The reaction of gas-phase atomic hydrogen with hydrogen atoms chemisorbed on a silicon surface is studied by use of the classical trajectory approach. Especially, we have focused on the mechanism changes with the hydrogen surface coverage difference. On the sparsely covered surface, the gas atom interacts with the preadsorbed hydrogen atom and adjacent bare surface sites. In this case, it is shown that the chemisorption of H(g) is of major importance. Nearly all of the chemisorption events accompany the desorption of H(ad), i.e., adisplacement reaction. Although much less important than the displacement reaction, the formation of $H_2(g)$ is the second most significant reaction pathway. At gas temperature of 1800 K and surface temperature of 300 K, the probabilities of these two reactions are 0.750 and 0.065, respectively. The adsorption of H(g) without dissociating H(ad) is found to be negligible. In the reaction pathway forming $H_2$, most of the reaction energy is carried by $H_2(g)$. Although the majority of $H_2(g)$ molecules are produced in sub-picosecond, direct-mode collisions, there is a small amount of $H_2(g)$ produced in multiple impact collisions, which is characteristic of complex-mode collisions. On the fully covered surface, it has been shown that the formation of $H_2(g)$ is of major importance. All reactive events occur on a subpicosecond scale, following the Eley-Rideal mechanism. At gas temperature of 1800 K and surface temperature of 300 K, the probability of the $H_2(g)$ formation reaction is 0.082. In this case, neither the gas atom trapping nor the displacement reaction has been found.

• 한국가스학회지
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• 제4권2호
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• pp.27-32
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• 2000

본 연구는 염화망간과 수산화나트륨을 이용하여 당량비에 따라 산화망간을 합성하였다. 합성된 산화망간의 결정구조와 비표면적을 측정하였으며, 이산화탄소의 분해 및 흡착에 대하여 연구하였다. 합성된 시료의 결정구조 분석결과 $Mn_3O_4$의 주피크가 나타났으며, 약간의 $MnO_2$와 $Mn_5O_8$도 관찰되었다. 또한 비표면적은 $13.92m^2/g{\~}32.33m^2/g$으로 측정되었다. 산화망간을 이용하여 $450^{\circ}C$에서 이산화탄소의 분해를 실시하였으며, 당량비 0.75에서 가장 잘 분해되었다. 이산화탄소의 화학흡착량을 측정한 결과 2.885cc/g${\~}$19.628cc/g으로 관찰되었으며, 이산화탄소의 흡착을 위한 최적당량비는 1.00이었다.

• 공업화학
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• 제28권2호
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• pp.221-229
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• 2017

본 연구에서는 다양한 상용 알루미나 지지체의 수소 상온산화 반응특성을 확인하기 위하여 활성금속 Pt를 기본으로 한 촉매에 습식함침법으로 제조하였다. 제조된 촉매들은 XPS, CO-chemisorption, BET를 이용하여 특성분석을 수행하였다. 다양한 $Pt/Al_2O_3$계 촉매는 열처리 조건에 따라서 촉매를 제조할 경우 전자 전하의 이동으로 발생하는 전기음성도 특성이 Pt의 산소종을 제어하였다. Pt의 담지량이 증가함에 따라 분산도가 감소하는 이유는 Pt의 HT (Huttig Temperature)에 기인한 것으로 보인다. 또한 상온에서 제어할 수 있는 최소 수소농도는 metallic Pt가 촉매 내 70.09% 이상에서 1.0 vol%까지 수소를 제어할 수 있었다.